Three dimensional (3D) displays have become very popular in consumer electronics market in recent years. Most 3D displays in the market come with a pair of shutter glasses which end users or consumers wear to view the 3D program. The shutter glasses are able to synchronize with a 3D projection, such as from a 3D television (TV), to separate left and right views for the consumer's eyes so as to generate a “3D” viewing experience. Some 3D TVs use polarized glasses, which also act to separate left and right eye views for an end user, although polarized glasses work in a different manner.
In principle, 3D display systems should not distort the colors of the original content. The end users or consumers at home or in a theater should see exactly the same color as colorists (or artists) can see in the post-production house. However, this fidelity is not achieved for current 3D display systems.
FIG. 1 illustrates the effects of various components in a current 3D system 100. FIG. 1 provides a representation of color shifting or color distortion caused by 3D systems employing 3D glasses. The color seen by the end user is different than that of the original post production content color. Post-production content 105 is shown having red (r) green (g) and blue (b) pixel content expressed as (r, g, b). When provided in 3D form, the r,g,b content is modified by a function f for each color content. That is, a function f operating on the red pixels modifies the red pixel content (fr(r)), a function operating on the green pixels modifies the green pixel content (fg(g)), and a function operating on the blue pixels modifies the blue pixel content (fb(b)). This function f is in effect the result of the response of the 3D display device being used. Thus, the 3D version content 110 of the (r,g,b) content, as displayed on a 3D display at 110 may be expressed as (fr(r), (fg(g)), (fb(b)). The addition of 3D glasses 115 can further modify the r,g,b content by applying a function g that operates on the output of the 3D display unit 110. Thus, the end user sees the interpreted 3D display 120 through the 3D glasses 115 as (grfr(r), ggfg(g), gbfb(b). More specifically, all 3D glasses currently on the market provide color shifting because of their lens arrangement. 3D glasses can thus distort the desired color originally intended from the content 105. This color distortion provided by the 3D glasses is undesirable in practical everyday consumer use. For example, some shutter glasses have a green tint which makes the whole picture appear greenish in color. Other shutter 3D glasses have a yellow tint which makes the whole picture appear to be yellowish in color.
Another common problem for 3D displays or 3D TVs is that the color distortion for the same content between their 2D and 3D mode changes, as shown in FIG. 2. Many 3D displays or 3D TVs have some kind of color compensation built in for 3D mode. But, when 3D glasses are worn in 2D mode, the inherent tint of the 3D glasses tints the entire picture for the user.
FIG. 2 illustrates color distortion in another system operating in a 3D mode. The 3D display 212 depicted in FIG. 2 may have built-in color compensation that operates differently than the present invention. The system 200 of FIG. 2 illustrates a post production pixel color content 205 of r,g,b. The 3D display can modify this color content via color compensation to be r′,g′,b′ as in 210. This can cause red, green, and blue function modifications 215 of the color compensated signal 210 resulting in (fr(r′), fg(g′), fb(b′). The 3D glasses worn by a user changes color functions resulting in (grfr(r′), ggfg(g′), gbfb(b′) as in 225. However, the color compensation in block 210 may be fixed such that over time, as elements of the 3D display 212 age, the r′,g′,b′ characteristics change resulting in age-related color distortions. This can cause color differences to appear as the user views 3D content using 3D glasses and even 2D content without using glasses. Currently, color re-calibration is not available to users for age-related color shifting.